1. Field of the Invention
The present invention relates to an apparatus for controlling the start of coating substrates with an adhesive and, more particularly, such an apparatus adapted to coat the adhesive on the substrates which, in turn, are assembled with an article conveyed one after another.
2. Description of Related Art
Technology of assembling substrates coated with an adhesive in advance with an article conveyed one after another includes, for example, an assembly of window glass panels with a vehicle body, as disclosed in U.S. Pat. No. 4,453,303. As the window glass panels are assembled with the vehicle body conveyed on a conveyor line, the conveyor line is provided with a window glass panel assembly station where a window glass panel assembly robot is disposed. To the window glass panel assembly station is connected a window glass panel conveyor line for supplying window glass panels to the robot, and this line is provided with an adhesive coating robot for coating the window glass panels with an adhesive. After the window glass panels are coated with the adhesive, the glass panels are transferred to the window glass panel assembly robot which, in turn, assembles the glass panels with the vehicle body.
In the assembly of the window glass panels with the vehicle body, it is important to timely match a timing of conveying the window glass panels with the timing of conveying the vehicle body. The vehicle bodies are conveyed via a conveyor line different from the conveyor line on which the window glass panels are conveyed so that the window glass panels to be assembled with the vehicle body should be conveyed in the window glass panel assembly line in a good time to be timely matched with the vehicle bodies to be conveyed one after another in the assembly station, enabling the assembly of the window glass panels with the body without a timely delay. Conventional technique involves synchronizing a conveyance tact of the window glass panels with the conveyance tact of the vehicle body.
In the assembly of vehicle bodies in the recent years, however, there is the growing tendency to assemble plural vehicle models on the same assembly line so that it is required to change the conveyance tact of the vehicle bodies several times a day. If the conveyance tact of the vehicle bodies would be changed in conventional techniques, a conveyance tact of the window glass panels should be changed so as to correspond to the tact system of the vehicle bodies. It should be noted, however, that the change of the conveyance tact of the window glass panels requires further changes of various steps involved with the conveyance of the glass panels, thus making control systems over a series of the steps complicated.
This is the issue, too, in applying an adhesive on substrates such as window glass panels to be conveyed in synchronization with the vehicle body conveyed one after another, on which the window glass panels are mounted.